I hold that the mark of a genuine idea is that its possibility can be proved, either a priori by conceiving its cause or reason, or a posteriori when experience teaches us that it is in fact in nature.

It is worth noting that the notation facilitates discovery. This, in a most wonderful way, reduces the mind's labour.

The knowledge which we have acquired ought not to resemble a great shop without order, and without an inventory; we ought to know what we possess, and be able to make it serve us in need.

When a truth is necessary, the reason for it can be found by analysis, that is, by resolving it into simpler ideas and truths until the primary ones are reached. It is this way that in mathematics speculative theorems and practical canons are reduced by analysis to definitions, axioms and postulates.

The words 'Here you can find perfect peace' can be written only over the gates of a cemetery.

God's relation to spirits is not like that of a craftsman to his work, but also like that of a prince to his subjects.

The present is big with the future, the future might be read in the past, the distant is expressed in the near.